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1   /*
2    * Created on Oct 18, 2005
3    *
4    * Copyright (c) 2005, the JUNG Project and the Regents of the University 
5    * of California
6    * All rights reserved.
7    *
8    * This software is open-source under the BSD license; see either
9    * "license.txt" or
10   * http://jung.sourceforge.net/license.txt for a description.
11   */
12  package edu.uci.ics.jung.graph;
13  
14  import java.util.Collection;
15  import java.util.Collections;
16  import java.util.LinkedHashMap;
17  import java.util.LinkedHashSet;
18  import java.util.Set;
19  
20  import org.apache.commons.collections15.Factory;
21  
22  import edu.uci.ics.jung.graph.util.EdgeType;
23  import edu.uci.ics.jung.graph.util.Pair;
24  
25  /**
26   * An implementation of <code>Graph</code> that orders its vertex and edge collections
27   * according to insertion time, is suitable for sparse graphs, and 
28   * permits directed, undirected, and parallel edges.
29   */
30  @SuppressWarnings("serial")
31  public class OrderedSparseMultigraph<V,E> 
32      extends SparseMultigraph<V,E>
33      implements MultiGraph<V,E> {
34  	
35      /**
36       * Returns a {@code Factory} that creates an instance of this graph type.
37       * @param <V> the vertex type for the graph factory
38       * @param <E> the edge type for the graph factory
39       */
40  	public static <V,E> Factory<Graph<V,E>> getFactory() { 
41  		return new Factory<Graph<V,E>> () {
42  			public Graph<V,E> create() {
43  				return new OrderedSparseMultigraph<V,E>();
44  			}
45  		};
46  	}
47  
48      /**
49       * Creates a new instance.
50       */
51      public OrderedSparseMultigraph()
52      {
53          vertices = new LinkedHashMap<V, Pair<Set<E>>>();
54          edges = new LinkedHashMap<E, Pair<V>>();
55          directedEdges = new LinkedHashSet<E>();
56      }
57  
58      @Override
59      public boolean addVertex(V vertex) {
60          if(vertex == null) {
61              throw new IllegalArgumentException("vertex may not be null");
62          }
63          if (!containsVertex(vertex)) {
64              vertices.put(vertex, new Pair<Set<E>>(new LinkedHashSet<E>(), new LinkedHashSet<E>()));
65              return true;
66          } else {
67          	return false;
68          }
69      }
70  
71  
72      @Override
73      public Collection<V> getPredecessors(V vertex)
74      {
75          if (!containsVertex(vertex))
76              return null;
77          
78          Set<V> preds = new LinkedHashSet<V>();
79          for (E edge : getIncoming_internal(vertex)) {
80          	if(getEdgeType(edge) == EdgeType.DIRECTED) {
81          		preds.add(this.getSource(edge));
82          	} else {
83          		preds.add(getOpposite(vertex, edge));
84          	}
85          }
86          return Collections.unmodifiableCollection(preds);
87      }
88  
89      @Override
90      public Collection<V> getSuccessors(V vertex)
91      {
92          if (!containsVertex(vertex))
93              return null;
94  
95          Set<V> succs = new LinkedHashSet<V>();
96          for (E edge : getOutgoing_internal(vertex)) {
97          	if(getEdgeType(edge) == EdgeType.DIRECTED) {
98          		succs.add(this.getDest(edge));
99          	} else {
100         		succs.add(getOpposite(vertex, edge));
101         	}
102         }
103         return Collections.unmodifiableCollection(succs);
104     }
105 
106     @Override
107     public Collection<V> getNeighbors(V vertex)
108     {
109         if (!containsVertex(vertex))
110             return null;
111 
112         Collection<V> out = new LinkedHashSet<V>();
113         out.addAll(this.getPredecessors(vertex));
114         out.addAll(this.getSuccessors(vertex));
115         return out;
116     }
117 
118     @Override
119     public Collection<E> getIncidentEdges(V vertex)
120     {
121         if (!containsVertex(vertex))
122             return null;
123         
124         Collection<E> out = new LinkedHashSet<E>();
125         out.addAll(this.getInEdges(vertex));
126         out.addAll(this.getOutEdges(vertex));
127         return out;
128     }
129 }